When no one was looking!

What is the silliest thing you did when you think no one was watching?

Sometimes when I'm alone in the washroom, and I'm using the hand-dryer, I would direct the gush of air towards my hair, such that my hair flies up. Kind of like a model photo shot . And I'll smile alluringly (I hope) and look in the mirror, imagining I'm a model or such.

What is the silliest thing you do when you thought no one was watching?